JP3196748B2 - heatsink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink used for an electronic component which needs to radiate heat because of a large heat generation.

[0002]

2. Description of the Related Art Conventionally, for electronic parts which need to radiate heat, a large number of grooves are formed in a grid on the upper surface of a rectangular parallelepiped block made of aluminum having a high thermal conductivity.
A heat sink having a large heat dissipation area by forming a large number of square pillar projections has been used.

A conventional heat sink will be described with reference to FIG. In FIG. 1A, a heat sink 100 has a large number of square pillar projections 101 formed on an upper surface thereof in order to enhance heat radiation efficiency. Then, as shown in FIG. 2B, the heat sink 100 is bonded to the BGA package 2 with a silicon-based adhesive 3 having high thermal conductivity, and the generated heat is released from the surface of the protrusion 101 to the atmosphere. Was.

However, as the performance and size of electronic components have recently become higher and smaller, the amount of heat generated per unit volume of the electronic components, that is, the heat generation density, has been increased. As a result, it is necessary to increase the amount of heat radiation per unit surface area. I am pressed for sex. But,
The heat sink 100 is used to increase the amount of heat radiation.
Raise the protrusion 101 or move the heat sink 10
By increasing the value of 0, the heat radiation area can be increased and the heat radiation amount can be increased. However, since the dimension in the height direction increases, there is a problem that the product cannot be made thin. Furthermore, when the heat sink 100 is made larger, the weight increases. Particularly, in an electronic component using the solder ball 2a, there is a concern that the weight acts on the solder ball 2a, and the long-term reliability of the electronic component is reduced. There's a problem.

As another conventional example, in recent years, BGA
(Ball Grid Array) With the spread of miniaturized and integrated electronic components having a high heat generation density, such as packages, various heat radiators using micro heat pipes have been proposed. Further, as a heat radiator using a micro heat pipe, for example, in order to cool a CPU (Central Processing Unit), it may be used for a frame made of aluminum for housing a wiring board. However, such heat radiators must be appropriately modeled in order to analyze the heat radiation characteristics, because the heat absorbing part and the heat radiating part have a complicated integrated structure and the use of micro heat pipes. However, there is a problem that it is difficult to analyze accurately and it is not possible to simplify the design of the heat sink.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is thin and lightweight with respect to an increase in the heat generation density of an electronic component. It is an object of the present invention to provide a heat sink capable of performing a simplified heat sink design based on the heat sink.

[0007]

According to a first aspect of the present invention, there is provided a heat sink for dissipating heat of an electronic component, wherein the heat sink has a circular or square outer shape made of a material having a high thermal conductivity. A plurality of micro heat pipes protruding horizontally from the heat absorbing portion toward the outer peripheral direction, and a larger than the outer shape of the upper surface of the electronic component.
An annular shape having an outer peripheral shape of a dimension , and having a circular or square inner peripheral shape having a dimension larger than the outer shape of the heat absorbing portion,
Contact the upper and lower positions of the micro heat pipe
A plate-shaped heat radiation fin made of a material having a high thermal conductivity is provided.

Thus, the heat sink can be made thinner and lighter.
Can be quantified, resulting in a thinner and lighter device
Can be performed, and the weight is added to the electronic components.
To prevent the long-term reliability of electronic components from deteriorating.
be able to.

Also, the high heat conduction of the micro heat pipe
The heat of the heat absorbing part is efficiently transmitted to the radiation fins by the rate
And high heat radiation performance can be exhibited. Sa
In addition, when analyzing the heat radiation characteristics, the heat absorption part and the heat radiation part are separated.
The heat transfer during this time is micro heat pipe
By doing so, appropriate modeling becomes possible,
A simplified heat sink design can be performed.

[0010] Further , the radiation fin may be connected to the micro heat path.
By gluing to the upper and lower positions of the
Dissipates the heat transmitted by the ikro heat pipe more effectively
Can improve the heat dissipation performance of the heat sink
Can be.

According to a second aspect of the present invention, in the heat sink according to the first aspect , the heat radiation fins are provided with a plurality of heat radiation holes. Thus, the heat radiation performance can be improved by the hot air convection between the upper surface and the lower surface of the radiation fin.

The invention described in claim 3 is the first or second invention.
In the heat sink described above, the micro heat pipe is bent from a central portion, and the bent portion is provided in the heat absorbing portion. Thereby, the heat transfer efficiency between the micro heat pipe and the heat absorbing portion can be improved, and as a result, the heat radiation performance of the heat sink can be improved, and the number of micro heat pipes used can be reduced.

According to a fourth aspect of the present invention, in the heat sink according to any one of the first to third aspects, the radiating fin is provided with at least three or more legs. Thus, the heat sink is supported only by the miniaturized electronic component, thereby preventing, for example, applying an external force to the end of the heat sink to damage the electronic component, particularly the solder ball. it can.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. A first embodiment of the heat sink will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a heat sink, which is composed of a heat absorbing portion 11, a micro heat pipe 12, and a radiating fin.

The heat absorbing portion 11 has a circular flat plate-like structure made of aluminum, which is a material having high thermal conductivity, and its lower surface is bonded to an electronic component. Here, the lower surface of the heat absorbing portion 11 has an area capable of efficiently absorbing the heat generated by the electronic component. Preferably, the diameter of the circle is set to a range larger than the length of one side of the electronic component and smaller than the length of the diagonal line. good. Further, the heat absorbing portion 11 is structured so as not to be unnecessarily thick, and the micro heat pipe 12 is inserted into the insertion hole 11.
In the case of a structure protruding from a, specifically, when the diameter of the micro heat pipe 12 is 3 mm, for example,
Desirably, the thickness is about 4-5 mm.

On the side surface of the heat absorbing portion 11, there are provided insertion holes 11a in which eight micro heat pipes 12 are projected radially in the horizontal direction.
A rivet mounting hole 11b is provided so as to penetrate through the rivet.
After the micro heat pipe 12 is inserted into the insertion hole 11a, the rivet 13 is driven into the rivet mounting hole 11b, so that the micro heat pipe 12 is fixed to the heat absorbing portion 11. As described above, the micro heat pipe 12 can satisfactorily absorb the heat of the heat absorbing section 11 by reliably contacting the heat absorbing section 11.

Since the micro heat pipes 12 have the same length and are arranged at equal intervals, each micro heat pipe 12 can transmit the same amount of heat to the radiation fins 14. In the present embodiment,
Although eight micro heat pipes 12 are used, the present invention is not limited to this. Specifically, the performance of the micro heat pipe 12, the heat value of the electronic components,
4 is determined by analyzing the heat radiation characteristics according to various conditions such as the heat radiation amount.

The radiating fins 14 have a thin plate-like structure made of aluminum having a high thermal conductivity, and have an annular shape having a circular outer and inner peripheral shape. More specifically, the diameter of the outer periphery is larger than the outer dimensions of the electronic component to be cooled, and the diameter of the inner periphery is larger than the outer diameter of the heat absorbing portion 11. Is set so that the required surface area is obtained from. Although not shown, the radiating fins 14 are bonded to the upper position of the micro heat pipe 12 with a silicon-based adhesive having a high thermal conductivity, and the heat of the micro heat pipe 12 is transmitted to the radiating fins 14 well. Heat is radiated from the surface of the radiation fins 14. Therefore, the heat sink 1 has a gap space 15 between the outer shape of the heat absorbing portion 11 and the inner periphery of the heat radiation fins 14, and can perform simplified modeling in analyzing the heat radiation characteristics. It has a structure that can be easily calculated.

The operation of the first embodiment configured as described above will be described with reference to FIG. In FIG. 1B, reference numeral 1 denotes a heat sink, which is bonded to the upper surface of the mounted BGA package 2 using a silicon-based adhesive 3. Here, when the heat sink 1 is bonded to the BGA package 2, the positional relationship can be visually observed from the gap space 15, so that the displacement and the defective protrusion of the adhesive 3 can be prevented.

The BGA package 2 generates heat in the operating state, and the heat is transmitted to the adhesive 3 and absorbed by the heat absorbing portion 11. Then, the heat is transmitted to the micro heat pipe 12, and the heat is very efficiently transferred from the end on the heat absorbing portion 11 side to the end on the radiation fin 14 side. And the radiation fins 14
The heat transmitted to the side is transmitted to the radiation fins 14 and is radiated from the surface of the radiation fins 14 to the atmosphere. Here, since the heat sink 1 has a structure that is point-symmetric with respect to the center of the heat absorbing portion 11, the heat generated by the BGA package 2 is:
The heat is radiated almost uniformly from the heat radiation fins 14.

Here, the heat radiation performance of the heat sink 1 can be easily set by increasing or decreasing the surface area of the radiation fin 14. Therefore, in order to enhance the heat radiation performance, the surface area of the heat radiation fins 14 may be increased. Needless to say, it is not necessary to increase the heat sink 1 by increasing the heat radiation fins 14, so that the device can be made thinner.

Even if the heat dissipating fins 14 are enlarged, the weight of the heat sink only increases by the increment of the heat dissipating fins 14 and the increment of the micro heat pipe 12, so that the weight does not increase so much. it can.
Furthermore, the weight reduction can reduce adverse effects due to the weight of the heat sink 1, for example, damage to the solder balls of the BGA package 2 and falling-off failure of the heat sink 1 due to a shortage of the adhesive 3, thereby lowering long-term reliability. Can be prevented.

Further, the structure having the heat radiating fins 14 independent of the high-performance heat transfer means by the micro heat pipe 12 facilitates the analysis of the heat radiating characteristics of the heat sink 1 and makes it possible to obtain a simulation result with few errors. Therefore, the design of the heat sink 1 can be simplified. Here, in the present embodiment, the analysis can be performed more easily by making the outer shape of the heat absorbing portion 11 and the outer shape and the inner shape of the radiation fin 14 circular. In the development and design of the device, it is necessary to comprehensively design the housing, the wiring board, etc. in consideration of the thermal characteristics in order to reduce the size and thickness of the device. The fact that the heat radiation characteristics can be easily and accurately analyzed is a very significant effect.

As described above, by using the heat sink of the first embodiment, it is possible to reduce the size and thickness of the device and to simplify the design of the heat sink, resulting in a new heat sink. It can have a great effect in developing products.

Next, a second embodiment of the heat sink will be described with reference to the drawings. In FIG. 3, reference numeral 1a denotes a heat sink, and a heat absorbing portion 21, a micro heat pipe 2
2 and the radiation fins 24 and 24a.

The heat-absorbing section 21 is composed of a rectangular flat upper heat-absorbing section 21a and a lower heat-absorbing section 21b made of aluminum which is a material having high thermal conductivity.
Is adhered to the BGA package 2. here,
The lower surface of the lower heat absorbing portion 21b has substantially the same size and shape as the external dimensions of the electronic component, and can efficiently absorb heat of the electronic component. Further, a groove 21d sandwiching the micro heat pipe 22 is formed in the upper heat absorbing portion 21a and the lower heat absorbing portion 21b, and the shape of the surface of the groove 21 d makes good contact with the surface of the micro heat pipe 22. ,
Heat can be efficiently transmitted to the micro heat pipe 22. The lower heat absorbing portion 21b and the upper heat absorbing portion 21a
Is fixed by driving the rivet 23 into the rivet mounting hole 21c with the micro heat pipe 22 interposed therebetween.

The micro heat pipe 22 has a structure in which the central portion is bent at a right angle, and is sandwiched so that the bent portion 22 a is located at the center of the heat absorbing portion 21. Further, in the present embodiment, two micro heat pipes 22 are used, but since the bent portion 22a also participates in heat transfer, it is equivalent to a structure in which four micro heat pipes 22 protrude. The above heat transfer effect can be obtained. Here, the micro heat pipe 22 has a structure protruding diagonally from the heat absorbing portion 21, and can efficiently absorb heat from the heat absorbing portion 21.

The radiating fins 24 have a structure formed of an annular thin plate having a rectangular outer peripheral shape and an inner peripheral shape, and are bonded to the upper position of the micro heat pipe 22 with a silicon-based adhesive. Specifically, the outer dimensions are larger than the outer dimensions of the BGA package 2 to be cooled, and the inner dimensions are larger than the outer dimensions of the heat-absorbing portion 11. Is set so that the required surface area is obtained from. Therefore, the heat sink 1a has a gap space 25 between the outer shape of the heat absorbing portion 21 and the inner periphery of the heat radiation fins 24, and can perform simplified modeling in analyzing the heat radiation characteristics. It has a structure that can be easily calculated. Further, the radiation fins 24 are attached so that the micro heat pipe 22 is located on a diagonal line of the radiation fins 24,
The heat of the micro heat pipe 22 is effectively dissipated by the radiation fin 2
4 can be told. Furthermore, the radiation fins 24
Are provided with a plurality of heat radiation holes 24c substantially uniformly so that hot air on the lower surface side can move to the upper surface side.

Similarly, a lower heat radiating fin 24a is adhered to a lower position of the micro heat pipe 22, and the heat radiating performance of the heat sink 1a can be improved by increasing the heat radiating area. Here, the lower radiation fin 2
Since the heat radiating holes 24c are also provided on the surface of 4a, the hot air between the upper heat radiating fins 24 can be efficiently moved, and the heat radiating performance can be improved.

Further, at the center of each side of the outer shape of the lower radiating fin 24a, a leg 24b is provided so as to project therefrom.
The stability when b is attached can be improved. Specifically, since the heat sink 1b is only supported by being adhered to the upper surface of the electronic component, when the electronic component is miniaturized, the supporting strength of the heat sink 1b decreases. However, since the heat sink 1b is supported by the legs 24b, the heat sink 1b can be stabilized and the danger of damaging the electronic components can be eliminated. When the BGA package 2 is installed on the lower side (in the direction of gravity drop) depending on the specifications of the device, it is preferable to fix the leg 24b to the object using a means such as a screw.
Other structures are the same as in the first embodiment.

The operation of the second embodiment configured as described above will be described with reference to FIG. The BGA package 2 generates heat in the operating state, and the heat is transmitted to the adhesive 3 and is absorbed by the heat absorbing portion 21. And the heat is
The heat is transmitted to the micro heat pipe 22 and is transferred to the heat radiation fins 24 very efficiently. Here, since the micro heat pipe 22 has the bent portion 22a, the number of micro heat pipes 22 used can be reduced, and the contact area with the heat absorbing portion 21 can be increased by the amount of the bent portion 22a. Therefore, the heat transfer efficiency can be improved.

The heat transmitted to the radiation fins 24 is transmitted to the upper radiation fins 24 and the lower radiation fins 24a.
Heat is released from these surfaces into the atmosphere. Here, the provision of the lower radiating fins 24a increases the radiating area, so that the radiating performance of the heat sink 1 can be improved. Further, since the heat radiating holes 24c are provided, the hot air can easily move and the heat radiating performance can be improved.

Further, since the heat sink 1a is supported by the legs 24b, the stability of the heat sink 1a is not deteriorated even if the heat radiation fins 24 become large or the BGA package 2 becomes small. BGA
Damage to the package 2 can be prevented. Other operations are the same as those of the first embodiment.

As described above, by using the heat sink of the second embodiment, it is possible to provide a heat sink having high heat radiation performance and capable of preventing damage failure to electronic components. In addition, by bending the heat sink, the number of heat sinks to be used can be reduced without lowering the heat radiation performance, and the cost of parts can be reduced.

In the above-described embodiment, an example in which the present invention is configured under specific conditions has been described. However, the present invention includes various embodiments. In the above-described embodiment, the fixing means using rivets is used as the means for fixing the micro heat pipe to the heat absorbing portion, but it may be fixed using screws. Further, the outer peripheral shape and inner peripheral shape of the radiation fin and the outer shape of the heat absorbing portion can be freely selected from circular or square, respectively.For example, for example, the outer peripheral shape of the radiation fin is made square, The peripheral shape may be circular, and the outer shape of the heat absorbing portion may be square.
Also, the radiation fins are not limited to flat plates,
In order to increase the surface area, a radiating fin having a pleated shape may be used. Further, the bonding means between the micro heat pipe and the heat absorbing portion or the heat radiating fin is not limited to the above embodiment. For example, the heat absorbing portion or the heat radiating fin may be caulked to the micro heat pipe.

[0036]

As described above, according to the heat sink of the present invention, a heat sink having a thin structure can be obtained.
Further, since the weight can be reduced, the device can be made thinner and lighter. Further, by reducing the weight, the danger that the weight of the heat sink acts on the electronic component, and particularly the long-term reliability of the solder ball is reduced can be eliminated. In addition, by separating the heat-absorbing part from the heat-dissipating fins and adopting a structure in which the micro heat pipe transfers the heat of the heat-absorbing part to the heat-dissipating fins, it is possible to effectively model the heat dissipation characteristics and to design the heat sink Can be simplified. Therefore, by using the heat sink of the present invention, it is possible to accurately simulate the thermal characteristics from the beginning of development in developing a thinned and miniaturized device, thereby shortening the development period. it can.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic diagrams of a heat sink according to a first embodiment, in which FIG. 1A is an enlarged top view and FIG. 1B is an enlarged cross-sectional view taken along the line AA ′.

FIGS. 2A and 2B are schematic views of the heat sink according to the first embodiment in an attached state, in which FIG. 2A is an enlarged top view and FIG. 2B is an enlarged cross-sectional view taken along the line AA ′.

FIGS. 3A and 3B are schematic diagrams of the heat sink according to the second embodiment in an attached state, in which FIG. 3A is an enlarged top view and FIG. 3B is an enlarged cross-sectional view taken along line AA ′.

FIGS. 4A and 4B are schematic views of a conventional heat sink in an attached state, wherein FIG. 4A is an enlarged top view, and FIG.
FIG. 3 shows an enlarged cross-sectional view of A ′ cross section.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 heat sink 1 a heat sink 2 BGA package 2 a solder ball 3 adhesive 11 heat absorbing portion 11 a insertion hole 11 b rivet mounting hole 12 micro heat pipe 13 rivet 14 radiation fin 15 gap space 21 heat absorbing portion 21 a upper heat absorbing portion 21 b lower heat absorbing portion 21 c rivet mounting Hole 21d Groove portion 22 Micro heat pipe 22a Bent portion 23 Rivets 24 Upper radiation fin 24a Lower radiation fin 24b Leg 25 Gap space 100 Heat sink 101 Projection

Claims (4)

(57) [Claims] 1. A heat sink for radiating heat of an electronic component, comprising: a heat absorbing portion having a circular or square outer shape made of a material having high thermal conductivity; and a plurality of micro-projections horizontally protruding from the heat absorbing portion toward an outer peripheral direction. A heat pipe, having an outer peripheral shape having a size larger than an outer shape of the upper surface of the electronic component
And an inner peripheral shape having a size larger than the outer shape of the heat absorbing portion.
A ring having an upper position of the micro heat pipe .
A heat sink comprising: a plate-shaped heat-dissipating fin made of a material having a high thermal conductivity, which is adhered to the lower and upper positions . 2. A heat sink according to claim 1, characterized in that a plurality of heat radiation holes in the heat dissipating fins. Wherein the micro heat pipe is bent from the central portion, according to claim 1 or 2 heatsink wherein it has disposed the bending portion to the heat absorbing portion. Wherein said radiation fin, any one heatsink according to claim 1 to 3, characterized in that a least three places or more legs.